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Photos - serie 1

Back to abstract 4.1) Mineralogy 4.2) Structure

Knauern are veins (tension gashes) composed of quartz, plagioclase and characteristically kyanite and/or andalusite (aluminosilicate polymorphs: Al2SiO5). Other minerals can be present as a function of the surrounding rock chemistry. For example, in micaschists with porphyroblasts of staurolite, concentrations of staurolite and kyanite can appear in the vein. Tourmaline can also be present in the metasediments and can be concentrated in some veins (see next page).

In the area of Alpe Larecc, kyanite appears first and andalusite comes in retromorphosis of kyanite. This is shown by the structural and textural analysis in the field and in thin section and the oxygen isotopes analysis (see the chapter "thermobarometry").

Sample of Knauern
Kyanite- and andalusite-bearing vein sample

Retromorphosis of Ky in And
Rod of kyanite (in blue, on the left) partially retromorphosed in andalusite (in pink, on the right)

And blast with Ky inclusions
View in thin section of an idiomorphic monocristal of andalusite with numerous inclusions of kyanite

1) Introduction | 2) Structural | 3) Thermobarometry | 4) TENSION GASHES | 5) Cartography | Bibliography | Thanks
Aluminosilicate-bearing veines: 4.1) MINERALOGY | 4.2) Structure | 4.3) Examples | 4.4) Formation

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Photo - serie 2

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Created: 10th May 2003
Last update: 3rd March 2012